Characterization and control system and method for a resin

ABSTRACT

The present disclosure is directed to a method of altering chemical properties of an in-process resin used with a 3D printing apparatus. The method includes monitoring the in-process resin using an imaging spectrometer, comparing the in-process resin and a model using one or more spectrums from the imaging spectrometer, and diluting the in-process resin with a diluting resin.

FIELD OF THE INVENTION

The present subject matter relates generally to control and alterationof chemical properties of a resin.

BACKGROUND OF THE INVENTION

Additive manufacturing or 3D printing is often used for creating modelsusing a liquid photopolymer resin (resin). The models may further beused as casting molds, prototypes, patterns, or end products. 3Dprinting is able to create complex designs of a desired surface finishthat may not otherwise be created through other machining ormanufacturing methods. For example, stereolithography (SLA) castingmolds may be used to manufacture turbine airfoils.

When 3D printing is used to create casting molds, the quality of theresulting component produced by casting is at least in part dependent onthe quality of the model. The quality of the model is at least in partdependent on the quality of the resin. While the quality, includingchemical and physical characteristics, of the resin is generally knownprior to production of models, as the resin ages, chemical and physicalcharacteristics of the resin alter toward depletion, in which the resinloses its ability to produce models. Depletion of the resin results inan increased occurrence of model crashes, in which the resin of themodel fails to properly cure or harden, resulting in a loss of geometry,tolerances, or desired surface finish, and ultimately discarding of themodel and the resin. Depletion of the resin often occurs before theentire quantity of resin is consumed (i.e. the useful life of the resinis expiring before the physical quantity of resin is consumed), therebyresulting in wasted resin, scrapped models, and increased costs.

Therefore, a need exists for a system and method for controllingchemical properties of a resin as the resin ages.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

The present disclosure is directed to a method of altering chemicalproperties of an in-process resin used with a 3D printing apparatus. Themethod includes monitoring the in-process resin using an imagingspectrometer, comparing the in-process resin and a model using one ormore spectrums from the imaging spectrometer, and diluting thein-process resin with a diluting resin.

A further aspect of the present disclosure is directed to acomputer-implemented method of characterizing and altering chemicalproperties of an in-process resin used with a 3D printing apparatus. Thecomputer-implemented method includes receiving, by one or more computingdevices, one or more first spectrums from an imaging spectrometer, inwhich the one or more first spectrums define at least one absorbancevalue versus a wavenumber for the in-process resin. Thecomputer-implemented method further includes receiving, by one or morecomputing devices, one or more second spectrums from the imagingspectrometer, in which the one or more second spectrums define at leastone absorbance value versus a wavenumber for a model. Thecomputer-implemented method further includes identifying, by one or morecomputing devices, a standard peak based at least in part on comparingthe one or more first spectrums and the one or more second spectrums;identifying, by one or more computing devices, at least one chemicalconstituent peak indicating depletion of a chemical constituent based atleast in part on comparing the one or more first spectrums and the oneor more second spectrums; determining, by one or more computing devices,at least one peak ratio based at least in part on the standard peak andat least one chemical constituent peak; and generating, by one or morecomputing devices, a life cycle of the in-process resin based at leaston an operating range of the at least one peak ratio.

A still further aspect of the present disclosure is directed to a systemfor characterizing and controlling chemical properties of an in-processresin. The system includes a 3D printing apparatus including thein-process resin and configured to generate a model, an imagingspectrometer configured to output at least one spectrum defining atleast one absorbance value versus a wavenumber for each of thein-process resin and the model, and a computing device configured tooperate the 3D printing apparatus and the imaging spectrometer.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 is a diagram of an exemplary characterization and control systemfor a resin;

FIG. 2 is an exemplary spectrum from the exemplary system shown in FIG.1;

FIG. 3 is an exemplary resin gradation generated from the exemplarysystem shown in FIG. 1;

FIG. 4 is an exemplary control chart generated from the exemplary systemshown in FIG. 1;

FIG. 5 is a flowchart outlining steps performed by the disclosed methodof characterization and control of chemical properties of a resin; and

FIG. 6 is another exemplary embodiment of a characterization and controlsystem for a resin.

Repeat use of reference characters in the present specification anddrawings is intended to represent the same or analogous features orelements of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

As used herein, the terms “first”, “second”, and “third” may be usedinterchangeably to distinguish one component from another and are notintended to signify location or importance of the individual components.

Characterization and control methods and systems for chemical propertiesof a resin while in use with a 3D printing apparatus is generallyprovided. The methods and systems of characterization improve upon resincharacterization and control by determining a life cycle of the resin inuse with a 3D printer and returning the resin to a known and repeatablechemical state. Restoration to known, repeatable, and quantifiablechemical properties mitigates model crashes and prevents resin waste dueto depletion of the resin prior to consumption of the resin.

Although the disclosure below references specific chemical constituentsand compositions of a photopolymer resin, the present disclosure isapplicable generally to resins used for 3D printing, additivemanufacturing, and other polymeric systems, including, but not limitedto, stereolithography (SLA), optical fabrication, photo-solidification,solid free-form fabrication, solid imaging, rapid prototyping, resinprinting, fused deposition modeling (FDM), digital light processing(DLP), multi jet printing (MLP), and type printing.

Referring now to the drawings, FIG. 1 is an exemplary embodiment ofcharacterization and control system for a resin 100 (herein referred toas “system 100”) used with a 3D printing apparatus 110 (herein referredto as “3D printer 110”). The system includes the 3D printer 110, animaging spectrometer 120, and a computing device 130. The 3D printer 110produces one or more models 112. The 3D printer 110 may include aplatform 113 immersed in a vat 114 filled with an in-process resin 116,as a liquid photopolymer resin, and a nozzle 118. In one embodiment, thenozzle 118 exposes ultraviolet (UV) light to the in-process resin 116 inthe vat 114 to produce the model 112 by curing the in-process resin 116.In various embodiments, the 3D printer 110 may further include an ovento bake the model 112 to further cure or harden the photopolymer resinwithin the model 112.

The system 100 further includes a computing device 130. The computingdevice 130 includes one or more processors 132 and one or more memorydevices 134. The one or more memory devices 134 stores instructions 136that, when executed by the one or more processors 132, cause the one ormore processors to perform operations. The operations of the computingdevice 130 are further described herein.

In one embodiment of the system 100, the computing device 130 controlsthe 3D printer 110. In one example, a 3D model (e.g. CAD model) of adesired model 112 is uploaded to the computing device 130. The computingdevice 130 divides the 3D model into a multitude of thin layers. Thecomputing device 130 controls, articulates, and operates the nozzle 118to expose each thin layer of the in-process resin 116 to UV light,thereby curing the thin layer of the in-process resin 116 into a portionof the model 112. The computing device 130 may further control,articulate, and operate the platform 113 within the vat 114. Theplatform 113 may rotate or translate to further expose each thin layerof the in-process resin 116 to UV light in conjunction with operation ofthe nozzle 118.

In other embodiments of the 3D printer 110, the nozzle 118 deposits aquantity of the in-process resin 116 from the vat 114 onto the platform113. The computing device 130 controls the nozzle 118 to deposit aquantity of the in-process resin 116 over a multitude of thin layers.The nozzle 118 may further include a light emitting or heat emittingsource to cure the in-process resin 116.

In another embodiment of the system 100, the computing device 130controls the imaging spectrometer 120. In various embodiments, theimaging spectrometer 120 is an infrared spectrometer. In still otherembodiments, the imaging spectrometer 120 is a Fourier transforminfrared spectrometer employing a Fourier transform infraredspectroscopy technique. In one embodiment, the infrared spectrometerencompasses a near-infrared range of about 14000 cm⁻¹ to about 4000cm⁻¹. In another embodiment, the infrared spectrometer encompasses amid-infrared range of about 4000 cm⁻¹ to about 400 cm⁻¹. In stillanother embodiment, the infrared spectrometer encompasses a far-infraredrange of about 400 cm⁻¹ to about 10 cm⁻¹. In yet other embodiments, theinfrared spectrometer may encompass a combination of overlapping rangesof the near-infrared, mid-infrared, or far-infrared ranges. In still yetother embodiments, the imaging spectrometer may define other ranges,conventions, or units to describe the portion of the electromagneticspectrum in which the imaging spectrometer operates.

The imaging spectrometer 120 outputs one or more first spectrums 121defining at least one absorbance or emissions value versus a spectralrange of wavenumbers for the in-process resin 116. The first spectrum121 may define a percentage ranging from about 0 to about 100, or itsdecimal equivalent, or any subset therebetween. The spectral range ofwavenumbers may define a reciprocal centimeter.

The imaging spectrometer 120 outputs one or more second spectrums 122defining at least one absorbance or emissions value versus a spectralrange of wavenumbers for the model 112. In one embodiment, the secondspectrum 122 for the model 112 is produced from a model 112 from anunused or new in-process resin 116. For example, the second spectrum 122is produced from the model 112 in which the in-process resin 116 is ofknown chemical or physical characteristics prior to use to produce aplurality of models 112.

In various embodiment of the system 100, the computing device 130determines one or more chemical constituents of the in-process resin 116and correlates the one or more chemical constituents of the in-processresin 116 to at least one chemical constituent peak of the firstspectrum and/or second spectrum. In one embodiment, the computing device130 determines the one or more chemical constituents of the in-processresin 116 using a table, graph, chart, or document.

Referring now to FIG. 2, an exemplary embodiment of a graph 200 of thefirst spectrum 121 and the second spectrum 122 is provided. In variousembodiments, the first spectrum 121 and/or the second spectrum 122 maybe provided in other formats, such as, but not limited to, commaseparated value files, tables or tabulated data, spreadsheets,databases, or other graphical types, including at least an absorbance oremissions value corresponding to a wavenumber of a spectral range.

Referring to FIGS. 1 and 2, the computing device 130 of the system 100identifies a standard peak based at least in part on comparing the oneor more first spectrums and the one or more second spectrums. In oneembodiment, the standard peak is identified by a plurality of chemicalconstituents contributing to the absorbance or emissions value of a peakof the first and/or second spectrum. In the exemplary embodiment shownin FIG. 2, the computing device 130 outputs the graph 200 as an overlayof the first spectrum 121 and the second spectrum 122. The standard peak212 may appear where at least a substantial portion of chemicalconstituents contribute to an absorbance or emissions value 124 at awavenumber value 125. In another embodiment in which the in-processresin 116 includes one or more chemical constituents defining aninitiator chemical constituent and a reactive chemical constituent, thestandard peak 212 may include a chemical bond that is common to theinitiator chemical constituent and the reactive chemical constituent inthe in-process resin 116. In yet another embodiment, the standard peak212 may be defined as having a substantially similar absorbance value124 for the first spectrum 121 compared to the second spectrum 122.

As a non-limiting example where the in-process resin 116 and the model112 include 4,4′-Isopropylidenecyclohexanol, oligomeric reactionproducts with 1-chloro-2,3-epoxypropane; a 3-ethyl-3-hydroxymethyloxetane; an ethoxylated trimethylolpropane triacrylate esters; a mixedtriarylsulfonium hexafluorophosphate salts in propylene carbonate; and a1-hydroxycyclohexyl phenyl ketone, a carbon-oxygen single bond stretchmay appear in each chemical constituent and therefore contribute to theabsorbance or emission value 124 of the standard peak 212 at awavenumber 125 approximately similar between the first and secondspectrums 121, 122.

Referring still to FIGS. 1 and 2, the computing device 130 of the system100 identifies at least one chemical constituent peak 214 indicatingdepletion of a chemical constituent based at least in part on comparingthe one or more first spectrums 121 and the one or more second spectrums122. In various embodiments, the in-process resin 116 may include one ormore of a solvent, an epoxy, and/or an oxetane.

In one embodiment, indications of depletion of a chemical constituentinclude indications of polymerization of the chemical constituents. Inone embodiment including the aforementioned chemical constituents, anammonia (CH) aromatic and a carbon-oxygen double bond in propylenecarbonate may diminish from the first spectrum 121 to the secondspectrum 122 at about the wavenumber for a chemical bond correspondingto a solvent in the initiator as a result of the polymerization processfrom the in-process resin 116 to the model 112. In another embodiment,indications of depletion of a chemical constituent including theaforementioned chemical constituents may diminish a reactive in thesecond spectrum 122 versus the first spectrum 121. In still anotherembodiment, indications of depletion of a chemical constituent mayinclude a change in wavenumber in the second spectrum 122 versus thefirst spectrum 121 for a reactive chemical constituent. For example,referring still to the aforementioned chemical constituents, the secondspectrum 122 may include a diminished magnitude of absorbance of areactive chemical constituent due to a depletion of a carbon-oxygensingle bond in an epoxy and/or oxetane.

Referring back to FIG. 1, the computing device 130 determines at leastone peak ratio based at least in part on the standard peak and at leastone chemical constituent peak. In one embodiment, the peak ratio is theabsorbance of a chemical constituent peak divided by the absorbance atthe standard peak. In another embodiment, the peak ratio is theabsorbance of a reactive chemical constituent peak divided by theabsorbance at the standard peak. In yet another embodiment, the peakratio is the absorbance of an initiator chemical constituent peakdivided by the absorbance at the standard peak.

The system 100 generates a life cycle 140 of the in-process resin 116based on at least an operating range of the at least one peak ratio. Invarious embodiments, the computing device 130 generates the life cycle140 of the in-process resin 116 based on one or more control charts(such as a control chart 141 shown in FIG. 4). In one embodiment, thelife cycle 140 includes at least one peak ratio from a reactive chemicalconstituent peak. In another embodiment, the life cycle 140 includes atleast one peak ratio from an initiator chemical constituent peak. Invarious embodiments, the life cycle 140 may include an upper controllimit, a lower control limit, and/or a moving range. In otherembodiments, the life cycle 140 may include an average moving range.

In various embodiments of the system 100, the computing device 130generates the life cycle 140 of the in-process resin 120 including aresin gradation (such as a resin gradation 150 shown in FIG. 3) based atleast on an operating range of the at least one peak ratio and one ormore standard deviations of the at least one peak ratio. Referring nowto FIGS. 1 and 3, in one embodiment, resin gradation 150 may be definedby ranges of peak ratios 152, 153 determined by the computing device130. The resin gradation 150 may define a plurality of resin grades 151.In the embodiment shown in FIG. 3, the resin gradation 150 defines at(152) a Grade 1 resin by a first initiator peak ratio range less thanI₁; a Grade 2 resin may be defined by a second initiator peak ratiorange between I₁ and I₂; a Grade 3 resin may be defined by a thirdinitiator peak ratio range between I₂ and I₃; and etc. until a Grade Nresin may be defined by an Nth initiator peak ratio range betweenI_(N−1) and I_(N). In another embodiment, the resin gradation 150defines at (153) a Grade 1 resin may be defined by a first reactive peakratio range less than R₁; a Grade 2 resin may be defined by a secondreactive peak ratio range greater than R₁; a Grade 3 resin may bedefined by a third reactive peak ratio range greater than R₂; and etc.until a Grade N resin may be defined by reactive peak ratio rangegreater than R_(N−1).

Referring now to FIGS. 1 and 4, the system 100 determines whether thein-process resin 116 is unexpired or expiring based at least on the lifecycle 140 of the in-process resin 116. In one embodiment, the computingdevice 130 determines whether the in-process resin 116 is unexpired orexpiring based at least on one or more control charts 141. The controlchart 141 may include a time-dependent axis 142 and an axis of peakratios 143. The control chart 141 may include one or more peak ratios144. In various embodiments, the computing device 130 defines a peakratio limit 145 at about or below which the in-process resin 116 isexpiring. In one embodiment, the in-process resin 116 is expired whenone or more peak ratios 144 is at about or below a peak ratio limit 145defined by a lower control limit of the peak ratios. In anotherembodiment, the in-process resin 116 is expired when one or more peakratios 144 is at about or below a peak ratio limit 145 defined by threestandard deviations below a median. In still other embodiments, thein-process resin 116 is expired when one or more peak ratios 144corresponding to a reactive chemical constituent and/or an initiatorchemical constituent is at about or below the peak ratio limit 145. Invarious embodiments, the peak ratios 144 are determined from a reactivechemical constituent or an initiator chemical constituent from thein-process resin 116.

Referring to FIGS. 3 and 4, in various embodiments, the resin gradation150 or the control chart 141 may further define resin grades 151 orranges of peak ratios 152, 153 by a number of standard deviations fromthe median of a sample population of peak ratios of the first quantityof resin 120. As a non-limiting example, where the median peak ratio forthe initiator chemical constituent is approximately 0.125 andapproximately 99.7 percent (or three standard deviations) of a normaldistribution of the sample population is desired to be captured of thepeak ratios, a peak ratio at or below three standard deviations belowthe median may define a Grade 1 resin; a range from the median to threestandard deviations below the median may define a Grade 2 resin; a rangefrom the median to three standard deviations above the median may definea Grade 3 resin; a range of an additional three standard deviationsabove Grade 3 may define a Grade 4 resin; and a range of an additionalthree standard deviations above Grade 4 may define a Grade 5 resin. Asanother non-limiting example, a Grade 5 resin may be defined by a rangeof peak ratios 152, 153 for a sample population of the unused in-processresin 116 (i.e. not previously used to create the model 112), or thein-process resin 116 used approximately once (i.e. used once previouslyto create the model 112).

Referring to FIG. 1, the system 100 dilutes the in-process resin 116with a diluting resin 117 based at least on whether the in-process resin116 is unexpired or expiring. In various embodiments, diluting thein-process resin 116 with the diluting resin 117 includes employing arule of mixtures. In one embodiment, the diluting resin 117 is an unusedliquid photopolymer resin. In another embodiment, the diluting resin 117is a previously used liquid photopolymer resin. In various embodiments,the diluting resin 117 includes similar chemical constituents as thein-process resin 116.

In various embodiments of the system 100, the computing device 130receives one or more of a third spectrum 123 from the imagingspectrometer 120, in which the one or more third spectrum 123 defines atleast one absorbance value versus a wavenumber for the diluting resin117. The computing device 130 further determines at least one peak ratiofor the diluting resin 117 based at least in part on the standard peak212 and at least one chemical constituent peak identified with thein-process resin 116. The computing device 130 may further determine arange of peak ratios for the diluting resin 117 from which to dilute thein-process resin 116.

In one embodiment of the system 100, the computing device 130 determinesthe range of peak ratios for the diluting resin 117 from which to dilutethe in-process resin 116 using a rule of mixtures. In anotherembodiment, using a rule of mixtures may include using the at least onepeak ratio of the diluting resin 117 and using the at least one peakratio of the in-process resin 116.

As a non-limiting example, a rule of mixtures is employed to calculate aquantity (e.g. weight, volume, etc.) of the diluting resin 117 at aknown peak ratio with which to dilute with a known quantity of thein-process resin 116. In one embodiment, a rule of mixtures is employedto determine a quantity of diluting resin 117 to achieve a desired peakratio for the in-process resin 116. In another embodiment, a rule ofmixtures is employed to determine a quantity of diluting resin 117 toachieve a desired resin grade 151 for the in-process resin 116 from theresin gradation 150.

Referring now to FIGS. 1-4, the diluting resin 117 and the one or morethird spectrum 123 may be implemented, configured, or otherwise executedsubstantially similarly as described in referenced to the in-processresin 116 and/or the one or more first spectrum 121. Additionally, asshown in FIG. 4, the control chart 141 may further include post-dilutionpeak ratios 149 demonstrating the return of the chemicalcharacterization of the in-process resin 116 to a known state followingdilution with the diluting resin 117.

Referring now to FIG. 5, a flowchart outlining exemplary steps of amethod to characterize and control chemical properties of an in-processresin 500 (herein referred to as “method 500”) is provided. Theflowchart of FIG. 5 may be implemented by one or more computing devices,such as the computing device 130 depicted and described relative toFIGS. 1 and 6. FIG. 5 depicts steps performed in a particular order forthe purposes of illustration and discussion. Those of ordinary skill inthe art, using the disclosures provided herein, will understand thatvarious steps of any of the methods disclosed herein can be adapted,modified, rearranged, omitted, or expanded in various ways withoutdeviating from the scope of the present disclosure.

The method 500 can include monitoring an in-process resin using animaging spectrometer, comparing the in-process resin and a model usingone or more spectrums from the imaging spectrometer, and diluting thein-process resin with a diluting resin. The method 500 can include at(502) receiving one or more first spectrums from an imagingspectrometer. The one or more first spectrums define at least oneabsorbance value versus a wavenumber for an in-process resin. At (504),the method 500 can include receiving one or more second spectrums fromthe imaging spectrometer. The one or more second spectrums define atleast one absorbance value versus a wavenumber for a model. For example,the one or more second spectrums 122 produced by the system 100described in regard to FIGS. 1 and 2 may be produced from an imagingspectroscopy of the model 112 from the imaging spectrometer 120. Themodel 112 may represent a baseline or desired output from the 3D printer110 of which may be desirably repeated with the in-process resin 116.

The method 500 can include at (506) identifying a standard peak based atleast in part on comparing the one or more first spectrums and the oneor more second spectrums. At (508), the method 500 can includeidentifying at least one chemical constituent peak indicating depletionof a chemical constituent based at least in part on comparing the one ormore first spectrums and the one or more second spectrums. In variousembodiments, the method 500 may further include comparing the one ormore first spectrums and the one or more second spectrums atcorresponding wavenumbers. In one embodiment, comparing the one or morefirst spectrums and the one or more second spectrums may includecomparing at ranges of wavenumbers to identify changes in magnitude ofabsorbance or emissions and/or identifying changes, or shifts, inwavenumbers relative to a magnitude of absorbance or emission.

The method 500 can include at (510) determining at least one peak ratiobased at least in part on the standard peak and at least one chemicalconstituent peak. For instance, determining at least one peak ratio mayinclude determining a peak ratio based on the standard peak and areactive chemical constituent peak. In another instance, determining atleast one peak ratio may include determining a peak ratio based on thestandard peak and an initiator chemical constituent peak. In stillanother instance, determining a peak ratio may include repeating one ormore steps of the method 500 over a period of time.

At (512), the method 500 can include generating a life cycle of thein-process resin based at least on an operating range of the at leastone peak ratio. In one embodiment, generating the life cycle of thein-process resin includes generating a resin gradation based at least onan operating range of the at least one peak ratio and one or morestandard deviations of the at least one peak ratio.

In various embodiments, the method 500 may further include at (514)determining whether the in-process resin is unexpired or expiring basedat least on the life cycle of the in-process resin. For instance,determining whether the in-process resin is unexpired or expiring mayinclude comparing a peak ratio to an operating range of the life cycle.In another instance, determining whether the in-process resin isunexpired or expiring may include comparing a peak ratio to a resingradation. In still another instance, determining whether the in-processresin is unexpired or expiring may include comparing a peak ratio to alower limit.

In another embodiment, the method 500 may further include at (516)receiving one or more third spectrums from the imaging spectrometer. Theone or more third spectrums define at least one absorbance value versusa wavenumber for a diluting resin. At (518), the method 500 may includedetermining at least one peak ratio for the diluting resin based atleast in part on the standard peak and at least one chemical constituentpeak identified with the in-process resin.

At (520), the method 500 may include determining a range of peak ratiosfor the diluting resin from which to dilute the in-process resin. In oneembodiment in which the vat 114 is limited by volume and/or weight,determining a range of peak ratios for the diluting resin from which todilute the in-process resin includes determining a minimum peak ratio ofthe diluting resin sufficient to dilute the in-process resin to adesired peak ratio and within the constraints of the vat 114 or system100. In another embodiment, determining a range of peak ratios for thediluting resin from which to dilute the in-process resin may includedetermining a quantity of diluting resin of a known peak ratio necessaryto dilute the in-process resin to a desired range of peak ratio.

The method 500 may include at (521) determining a range of peak ratiosto which to dilute the in-process resin. In one embodiment, a user mayinput to the computing device 130 a desired range of peak ratios towhich to dilute the in-process resin 116. In another embodiment, thecomputing device 130 may determine a range of peak ratios to which todilute the in-process resin 116 based at least on the life cycle 140.For instance, the range of peak ratios to which to dilute the in-processresin 116 may be a defined range from an operating range of thein-process resin 116. As another non-limiting example, the range of peakratios 152, 153 may be determined or chosen from the life cycle 140,such as, but not limited to, from the control chart or the resingradation.

The method 500 may include at (522) diluting the in-process resin with adiluting resin based at least on whether the in-process resin isunexpired or expiring. For instance, the computing device 130 of thesystem 100 may transmit a signal to the 3D printer 110 to mix thediluting resin 117 and the in-process resin 116 by determined quantitiesand/or to determined ranges of peak ratios.

At (524), the method 500 may further include determining one or morechemical constituents of the in-process resin. At (526), the method 500may include correlating the one or more chemical constituents of thein-process resin to at least one chemical constituent peak of the firstspectrum and/or second spectrum.

In various embodiments, the method 500 or portions thereof may beperformed iteratively. In one embodiment, the steps at (502), (504),(506), (508), (510), and (512) may be performed iteratively. In anotherembodiment, the aforementioned steps and (514) may be performediteratively. In still another embodiment, the aforementioned steps maybe performed and a portion of the steps, such as at (502), (510), (512),and (514) may be performed iteratively thereafter.

Referring now to FIG. 6, another exemplary embodiment of acharacterization and control system 100 for a photopolymer resin isprovided. The system 100 may include a 3D printer 110, an imagingspectrometer 120, and a computing device 130. The system 100 may furtherinclude one or more networks 160 to communicate within the system 100and/or externally of the system 100. The one or more processors 132 caninclude any suitable processing device, such as a microprocessor,microcontroller, integrated circuit, logic device, and/or other suitableprocessing device. The one or more memory devices 134 can include one ormore computer-readable media, including, but not limited to,non-transitory computer-readable media, RAM, ROM, hard drives, flashdrives, non-volatile storage devices, and/or other memory devices.

The system 100 may communicate via one or more network(s) 160, which caninclude any suitable wired and/or wireless communication links fortransmission of the communications and/or data, as described herein. Forinstance, the network 160 may include a SATCOM network, ACARS network,ARINC network, SITA network, AVICOM network, a VHF network, a HFnetwork, a Wi-Fi network, a WiMAX network, a gatelink network, etc.

The one or more memory devices 134 can store information accessible bythe one or more processors 132, including computer-readable instructions136 that can be executed by the one or more processors 132. Theinstructions 136 can be any set of instructions that when executed bythe one or more processors 132, cause the one or more processors 132 toperform operations. In some embodiments, the instructions 136 can beexecuted by the one or more processors 132 to cause the one or moreprocessors 132 to perform operations, such as any of the operations andfunctions for which the system 100 and/or the computing device 130 areconfigured, the operations for characterizing and controlling chemicalproperties of a photopolymer resin (e.g., method 400), as describedherein, the system for generating the life cycle of a photopolymer resinand/or diluting a photopolymer resin (e.g., system 100), thecharacterization and control system for a photopolymer resin, and/or anyother operations or functions of the one or more computing device 130.The instructions 136 can be software written in any suitable programminglanguage or can be implemented in hardware. Additionally, and/oralternatively, the instructions 136 can be executed in logically and/orvirtually separate threads on one or more processors 132. The one ormore memory devices 134 can further store data 138 that can be accessedby the processor(s) 132. For example, the data 138 can include the firstspectrum 121, the second spectrum 122, the third spectrum 123, thestandard peak 212, the chemical constituent peaks 214, the absorbance oremissions values 124, the wavenumber values 125, the one or more rangesof peak ratios 152, 153, the life cycle 140, the control charts 141, theresin gradation 150, and/or any other data and/or information describedherein.

The computing device 130 can also include a network interface 139 usedto communicate, for example, with the other components of system 100(e.g., via network 160). The network interface 139 can include anysuitable components for interfacing with one or more networks, includingfor example, transmitters, receivers, ports, controllers, antennas,and/or other suitable components.

The technology discussed herein makes reference to computer-basedsystems and actions taken by and information sent to and fromcomputer-based systems. One of ordinary skill in the art will recognizethat the inherent flexibility of computer-based systems allows for agreat variety of possible configurations, combinations, and divisions oftasks and functionality between and among components. For instance,processes discussed herein can be implemented using a single computingdevice or multiple computing devices working in combination. Databases,memory, instructions, and applications can be implemented on a singlesystem or distributed across multiple systems. Distributed componentscan operate sequentially or in parallel.

The systems 100 and methods 500 shown in regard to FIGS. 1-6 anddescribed herein may characterize and control chemical properties of anin-process resin as the chemical properties alter over time. The systemsand methods described herein may return the in-process resin to knownand desirable chemical properties following alteration to an unknownstate. Additionally, the method of diluting the in-process resin withthe diluting resin provides benefits over alternative methods. Forexample, since 3D printing, including vats, is generally limited byphysical properties such as space, weight, or volume, the methods andsystems disclosed may improve resin characteristics within a limitedphysical space. Additionally, the methods and systems disclosed mayreturn the in-process resin to a known chemical state and known state ofthe in-process life cycle in contrast to other methods. Still further,the methods and systems disclosed may reduce waste, and thereby providecost benefits, over other methods of dilution or characterization.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A method of altering chemical properties of anin-process resin used with a 3D printing apparatus, the methodcomprising: monitoring the in-process resin using an imagingspectrometer; comparing the in-process resin and a model using one ormore spectrums from the imaging spectrometer; and diluting thein-process resin with a diluting resin.
 2. The method of claim 1,further comprising: identifying a standard peak based at least in parton comparing one or more first spectrums and one or more secondspectrums from the imaging spectrometer.
 3. The method of claim 1,further comprising: identifying at least one chemical constituent peakindicating depletion of a chemical constituent based at least in part oncomparing one or more first spectrums and one or more second spectrumsfrom the imaging spectrometer.
 4. The method of claim 1, furthercomprising: determining at least one peak ratio based at least in parton a standard peak and at least one chemical constituent peak.
 5. Themethod of claim 1, further comprising: generating a life cycle of thein-process resin based at least on an operating range of the at leastone peak ratio.
 6. The method of claim 1, further comprising:determining a range of peak ratios to which to dilute the in-processresin with the diluting resin.
 7. The method of claim 1, furthercomprising: receiving one or more third spectrums from the imagingspectrometer, wherein the one or more third spectrums define at leastone absorbance value versus a wavenumber for a diluting resin; anddetermining at least one peak ratio for the diluting resin based atleast in part on the standard peak and at least one chemical constituentpeak identified with the in-process resin; and determining a range ofpeak ratios for the diluting resin from which to dilute the in-processresin.
 8. The method of claim 7, wherein determining the range of peakratios for the diluting resin from which to dilute the in-process resinincludes using a rule of mixtures.
 9. The method of claim 1, furthercomprising: determining a range of peak ratios to which to dilute thein-process resin with the diluting resin.
 10. A computer-implementedmethod of characterizing and altering chemical properties of anin-process resin used with a 3D printing apparatus, thecomputer-implemented method comprising: receiving, by one or morecomputing devices, one or more first spectrums from an imagingspectrometer, wherein the one or more first spectrums define at leastone absorbance value versus a wavenumber for the in-process resin;receiving, by one or more computing devices, one or more secondspectrums from the imaging spectrometer, wherein the one or more secondspectrums define at least one absorbance value versus a wavenumber for amodel; identifying, by one or more computing devices, a standard peakbased at least in part on comparing the one or more first spectrums andthe one or more second spectrums; identifying, by one or more computingdevices, at least one chemical constituent peak indicating depletion ofa chemical constituent based at least in part on comparing the one ormore first spectrums and the one or more second spectrums; determining,by one or more computing devices, at least one peak ratio based at leastin part on the standard peak and at least one chemical constituent peak;and generating, by one or more computing devices, a life cycle of thein-process resin based at least on an operating range of the at leastone peak ratio.
 11. The computer-implemented method of claim 1, whereingenerating a life cycle of the in-process resin includes generating aresin gradation based at least on an operating range of the at least onepeak ratio and one or more standard deviations of the at least one peakratio.
 12. The computer-implemented method of claim 1, furthercomprising: determining, by one or more computing devices, whether thein-process resin is unexpired or expiring based at least on the lifecycle of the in-process resin.
 13. The computer-implemented method ofclaim 1, further comprising: determining a range of peak ratios to whichto dilute the in-process resin.
 14. The computer-implemented method ofclaim 13, further comprising: receiving, by one or more computingdevices, one or more third spectrums from the imaging spectrometer,wherein the one or more third spectrums define at least one absorbancevalue versus a wavenumber for a diluting resin; and determining, by oneor more computing devices, at least one peak ratio for the dilutingresin based at least in part on the standard peak and at least onechemical constituent peak identified with the in-process resin; anddetermining, by one or more computing devices, a range of peak ratiosfor the diluting resin from which to dilute the in-process resin. 15.The computer-implemented method of claim 14, wherein determining therange of peak ratios for the diluting resin from which to dilute thein-process resin includes using a rule of mixtures.
 16. Thecomputer-implemented method of claim 15, wherein using a rule ofmixtures includes using the at least one peak ratio of the dilutingresin and using the at least one peak ratio of the in-process resin. 17.The computer-implemented method of claim 10, further comprising:diluting, by one or more computing devices, the in-process resin withthe diluting resin based at least on the life cycle of the in-processresin.
 18. The computer-implemented method of claim 10, furthercomprising: determining, by one or more computing devices, one or morechemical constituents of the in-process resin; and correlating, by oneor more computing devices, the one or more chemical constituents of thein-process resin to at least one chemical constituent peak of the firstspectrum and/or second spectrum.
 19. A system for characterizing andcontrolling chemical properties of an in-process resin, the systemcomprising: a 3D printing apparatus including the in-process resin andconfigured to generate a model; an imaging spectrometer configured tooutput at least one spectrum defining at least one absorbance valueversus a wavenumber for each of the in-process resin and the model; anda computing device configured to operate the 3D printing apparatus andthe imaging spectrometer.
 20. The system of claim 19, wherein the 3Dprinting apparatus further includes a diluting resin, and wherein thecomputing device is configured to dilute the in-process resin with thediluting resin based at least on a life cycle of the in-process resin.